1. Field of the Invention
The present invention relates to methods of and apparatus for manufacturing knitted articles. More particularly, the present invention relates to a methods of and apparatus for manufacturing knitted articles with looped-shaped stitches.
2. Technical Considerations and Prior Art
Weft knitting of textile fabrics with looped-shaped stitches has been practiced for many years. The prior art technique of weft knitting with looped-shaped stitches generally includes forming yarn into rows of loops by engaging and lifting the yarn with an array of needles. As the yarn is formed into loops, subsequent loops are inserted into pre-existing loops to hold the pre-existing loops in place and thereby form a stitch. As subsequent stitches are formed, a knitted fabric is generated.
In order to manufacture the fabric at high speed, it is necessary for the needles which engage the yarn to effect a very fast vertical movement away from the plane of the fabric being manufactured. This is because it is necessary for each needle to complete a stitch before a subsequent or following needle begins a subsequent stitch. In reality, while one stitch is being formed, the needle making the subsequent stitch begins its operation before the first stitch is complete. However, the number of needles which can be arrayed in an overlapping relationship remains quite limited. This, of course, limits the speed at which textile fabric may be manufactured.
With respect to the instant invention, a primary concern is basically with the speed of the yarn, as it is fed into the knitting machine rather than the speed of manufacturing the fabric per se.
Since each stitch is formed in sequence, and each stitch requires a definite amount of time, upper speeds of the manufacturing operation are limited to yarn feed speeds of not much more than 500 m/min. This is largely due to stresses exerted on the yarn, as well as stresses exerted on moving mechanical parts, such as the needles, needle hooks, latches, cams, etc.
In order to attain speeds approximately 500 m/min., knitting machines of increasing sophistication must be resorted to. This high degree of sophistication, of course, creates an economic limitation on the type of equipment which may be used.
In addition, it is necessary with the prior art approaches to stop the knitting machinery in order to permit the threading up of the yarn. In many instances, stopping the machine results in great inconvenience since other associated machines in the manufacturing line must also be either stopped, idled or have their product side-tracked.